In article , photo@best.com says...

>Hi. I recently picked up a Soligor Fish Eye lens at a garage sale and >am wondering if it can be adapted for use on a 4x5? (...)

If this is not just a front converter (it would be threaded at the
rear, like a filter), which, alas, doesn't work very well for 4x5,
it would be a prime lens, and no more adaptable than your 50mm to
the 4x5 format, except for shooting extreme closeups awkwardly and
not very well - it is best used on a 35mm camera, if that is what
it was designed to fit.
Hope This Helps